[R] Factor level with no cases shows up in a plot

Stefan Grosse singularitaet at gmx.net
Wed May 27 22:19:46 CEST 2009


Arthur Burke wrote:
>  
> ...  I get the four lines that I expected but the legend includes the
> Group level "cohort 4" .
>  
> How can I get rid of "cohort 4" in Group?
>   

This link might be of interest for you:
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-manip:drop_unused_levels

hth
Stefan



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